Process of solyency induction



y 2 1942- J. E. HARVEY, JR 3 3 I PROCESS OF SQLVENCY INDUCTION Filed March '14, 1941 we? aze WWW DAM/1 V DQL/ZAQTE bow/{ 06671447 /0/V swam tom Patented July 28, 1942 PROCESS OF SOLVENGY INDUCTION Jacquelin E. Harvey, .112, Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application March 1 1, 1941, Serial No. 383,464

5 Claims.

This invention relates to the production of solvents.

More specifically, the present invention relates to the induction of solvency in tars of aromatic content and fractions thereof, including pitches.

This application is a continuation in part of my application Sr. No. 352,653, filed August 14, 1940, for Process of solvency induction, copending herewith, as to all matter common to the two applications.

An object of the present invention is the induction of solvency in tars of aromatic content and fractions thereof by the step-wise action-of hydrogen.

Further objects of the present invention will become apparent from the following disclosures.

Starting materials of the present invention are tars of aromatic content and fractions thereof derived from coal, wood, petroleum, gas and/or gases. Especially attractive as a starting material is tar derived from coal, as for instance, coke oven tar, gas house tar, or low temperature tar. These tars derived from coal, and more especially coke oven tar, are characterized by the presence of high molecular complexes that are so susceptible to thermal degradation that the solvents of the present invention cannot be provided by a single action of hydrogen, but must be produced in step-Wise manner as hereinafter described. By the process of the present invention it is further possible by recycling operation to substantially convert the entirety of the starting material remaining liquid into the solvents of enhanced value.

The following examples will serve to illustrate general principles upon which the practice of the present invention is based, as well as the process of the present invention.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the figure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example 1.-A high residue creosote having substantially 48% boiling above 355 C. and substantially 2% coke residue is charged to a high pressure autoclave and subjected to the action of hydrogen at 200 atmospheres pressure and a temperature of 400 0.; catalyst molybdenum oxide; time of reaction, one hour. At the end of the'hour period the beneficiated creosote is withdrawn from the autoclave and will be found to have reduced coke residue, specific gravity and viscosity. The beneficiated material is then distilled to an upper limit of 250 C. to provide the distillate as an intermediate starting material. The intermediate starting material is then subjected in the autoclave to the further action of hydrogen wherein temperature is 475 C. and the pressure 200 atmospheres; catalyst molybdenum oxide. The thus beneficiated material will be found to have an increased solvency as compared to its intermediate starting material, and will be further characterized by having an increment of low boiling fractions in excess of fractional increment inthe higher boiling range. The residue incidental to above stripping operation is recycled for further solvent production. The first action of hydrogen is characterized by preferential action on the high boiling range.

Example 2.-A coal tar, specific gravity 1.1641, coke residue in excess of 8% and boiling predominantly above 190 C. is passed through a high pressure reaction vessel while-simultaneously flowing hydrogen therewith at a temperature of 410 C. and 350 atmospheres pressure; catalyst tin sulfide; time of reaction, 75 minutes; flow of hydrogen 12,000 cubic feet per .barrel feed. The beneficiated tar is distilled to .an upper limit of 260 C. to provide the distillate as an intermediate starting material. The intermediate starting material is then passed through a high pressure reaction vessel while simultaneously flowing hydrogen therewith; catalyst molybdenum sulfide; flow of hydrogen 6,000 cubic feet per barrel of feed stock andtime of contact two minutes. The beneficiated material will be found to have a solvency in excess of its intermediate starting material and willbe characterized by an increment of low boiling fractions in excess of fractional increment in the high boiling range.

Example 3.-A tar fraction of aromatic content, initial boiling point substantially 220 C. and having substantially a residue above 355 C. is subjected to the action of hydrogen While contacting a cobalt sulfide catalyst; temperature 410 C.; pressure 400 atmospheres; time of contact one hour. The beneficiated-material will be found to have a lowered coke residue specific gravity and viscosity, and a condensation of boiling points toward the lower end. The beneficiated material is distilled to an upper limit of 320 C. with the distillateserving as intermediate starting material. The intermediate starting material is subjected to the action of hydrogen at a temperature of 465 C. and a pressure of 200 atmospheres. The finally beneficiated material will be found to have a solvency in excess of its intermediate starting material and will be further characterized by an increment of low boiling fractions in excess of fractional increment in the higher boiling range.

Example 4.A coal tar pitch specific gravity 1.23 and 15% boiling at 355 C. is subjected to the action of hydrogen at 375 C. and 200 atmospheres pressure; catalyst molybdenum sulfide; time of contact one hour. The beneficiated pitch is again subjected to an identical cycle of hydrogenation. The twice beneficiated pitch is distilled to an upper limit of 210 C. to provide a distillate as an intermediate starting material for the solvents of the present process; the distillate is then subjected to the action of hydrogen at 535 C. and a pressure of 200 atmospheres. The beneficiated distillate will be found to have a solvency in excess of its intermediate parent material and will be further characterized by an increment of low boiling fractions in excess of fractional increment in the higher boiling range,

Example 5.-It has been discovered that when subjecting certain mixtures of refined coal tar fractions to the action of hydrogen in accordance with the present process for the production of solvents and/or plasticizers that the formerly accepted teaching that product increment, depolymerization and/or hydrogen absorption are linear functions of the time, is not followed.

When subjecting a mixture of crude coal tar fractions boiling predominantly above 250 C. or 275 C. to the action of hydrogen, research has disclosed that the newly induced products, depolymerization and/or hydrogen absorption are linear functions of the time. As an example, when the above mixture of crude coal tar fractions is subjected to the action of hydrogen for 2-, 5-, and 8-hour periods the newly induced products, depolymerization and/or hydrogen absorption were linear functions of the time element.

One of the preferred starting materials of the present process is a mixture of refined coal tar fractions boiling predominantly above 355 or 380 C. Such a starting material is conveniently the final residue resulting from evaporating coal tar to dryness or substantial dryness, and then stripping wood preservative from the distillate. This final residue mass of refined. coal tar fractions, is an especially suitable refined coal tar pitch to be used as starting material of the present process. However, in contradistinction to the mixture of crude coal tar fractions boiling predominantly above 250 or 300 (3., when the aforenamed preferred starting material is subjected to the action of hydrogen for production of solvents and/or plasticizers, the newly induced fractions, depolymerization and/or hydrogen absorption are not, as described for the other mixture of crude tar fractions, linear functions of the time. A critical period of treatment by or with hydrogen exists, and which if exceeded causes loss of newly induced fractions, polymerization and/or lessened hydrogen absorption on certain fractions of the preferred starting material under treatment.

The critical time element because of the obvious possible variations in the characteristics of the aforenamed refined coal tar pitch cannot be spoken of as an arbitrary figure. It can be stated, however, that if the refined coal tar pitch were to be subjected to the action of hydrogen for such a length of time, which for other coal tar fractions would illustrate that the newly induced fractions, depolymerization and/or hy-- drogen absorption were linear functions of the time element, loss of induced products, poly-- merization and/or lessening of hydrogen absorp tion would occur. When treating the refined coal tar pitch by or with hydrogen, the critical time element is in the order of about three hours.

In the disclosures made herein and in the appended claims distillate removal of low boiling portions from the beneficiated material is considered the equivalent of fractional removal by gas movement, solvent action or the like. The converse also obtains.

A refined coal tar pitch chosen from the group boiling predominantly above, and above 355 0., characterized by a predominance of ring structures, a specific gravity in excess of 1 and a Conradson carbon in excess of in the order of 4 is subjected to the action of hydrogen while contacting a sulfide catalyst selected from the group comprising the sixth and eighth periodic groups; temperature 410 0.; pressure 350 atmospheres and time of contact two hours. The beneficiated refined pitch will be found to have a lowered specific gravity, coke residue and Conradson carbon and a condensation of boiling points toward the lower end. The beneficiated refined coal tar pitch is stripped up 'to a temperature of 345- C. wth the lower boiling portion serving as an intermediate starting material. The intermediate starting material is then subjected to further hydrogen action at a temperature of 525 C. at a pressure of 200 atmospheres. The flow of hydrogen is controlled so that the finally beneficiated material will have a solvency in excess of its intermediate starting material and will be further characterized by an increment of low boiling fractions in excess of fractional increment in the higher boiling range. By the higher boiling range is meant, as an example, the upper half of the boiling range.

The gas flow in the first hydrogen action is controllably held at a rate in excess of the hydrogen action last named. In the first hydrogen action gas flows of 15,000-20,000 cubic feet per barrel material treated have proven satisfactory, however, higher or lower flows may be employed. In the hydrogen action on the intermediate starting material gas flows of in the order of 5,00 0-6,000 cubic feet per barrel material treated have proven satisfactory; however, lower flows may be employed under certain conditions with especially beneficial results fiowing therefrom. If desired, higher gas flow may be employed when treating the intermediate starting material.

When subjecting the refined coal tar pitch to the action of hydrogen the period of treatment in the first hydrogen action is held at or below the critical time element. If a time period greater than critical is employed loss of newly induced 5 products, polymerization and/or lessened hydrogen absorption will occur. Thus, the time element of the present process in the first hydrogen action when treating a refined coal tar pitch is so selected that fractional increment, depolymerization and/ or hydrogen absorption are linear functions of the time element. The critical time period of the first hydrogen action when treating a refined coal tar pitch is in the order of about three hours.

In the step-wise action of hydrogen in the present invention, the first action of. hydrogen on the starting material is characterized by reduction of cokeresidue, specific. gravity and viscosity in the starting material. In, the first cycle of hydrogen action pressures as low as atmospheres are usable as are temperatures as low as 200 0., however, higher temperatures and pressures are preferred, as for instance, but not as a restriction, temperatures of 350-450" C. and pressures of in excess of 200 atmospheres, Pressures and temperatures are, however, not restricted to any definite limitations inasmuch as hydrogen actions that reduce the coke residue, specific gravity and viscosity of the starting material will proceed at lowered temperatures and pressures. The desired temperatures and pressures are those that will reduce coke residue specific gravity and viscosity in a commercial manner. When using continuous operation in the first hydrogen cycle gas flows of l0,000-15,000 cubic feet per barrel feed stock has proven satisfactory, however, higher and lower gas flows have proven effective.

In the last cycle of hydrogen action, as comprising a part of the present invention, for a given coordination of temperature and pressure as compared to the first cycle, the hydrogen flow in the last cycle is less than the flow in the first cycle. In the last cycle of hydrogen action pressures as low as 50 atmospheres are usable as are temperatures as low as 250 C. However, more elevated pressures and temperatures are preferred, as for instance, pressures of in the order of 200 atmospheres and temperatures chosen from the range between 300-750 C.

Aromatic tars of petroleum derivation or as produced from gas or gases serve as suitable starting materials. Tars or fractions thereof, at least once refined by hydrogen or by other means also serve as starting material.

By the term beneficiated as used herein and in the appended claims is meant the starting or intermediate starting material at least once subjected to the action of hydrogen in accordance to the present process.

Catalysts assist in speeding and directing the desired reaction of the process of the present invention, All catalysts effective in the presence of hydrogen are usable. Catalysts may be. used in various shapes or forms; deposited in well known manner on carriers; cobalt, tin, vanadium, molybdenum, manganese, chromium, tungsten, or their compounds; promoted or not; in admixture if desired, with or without small amounts of acid, acids, halogen or derivatives of halogens; all sulfide and/or oxide hydrogenatin catalysts, in the form of shapes, pellets, extruded lengths, comminuted, with or without the presence of other materials possessing hy rogenating properties, or not, such as asbestos, quartz, earths, lumps of brick, etc.

In both cycles of hydrogenation, the present process is predicated on so controlling the reaction conditions that ring structures are not opened with the subsequent formation of liquid chain or paraffin structures to the extent that the solvents of enhanced solvency of the present invention are impossible to manufacture.

In the first cyclic action of hydrogen reaction, conditions are so controlled as to induce no substantial percentage of carbonaceous increment. When utilizing most of the starting materials, the first action of hydrogen is further characterized by the depolymerization of high molecular complexes. By the term high molecular complexes is meant those high boiling fractions especially susceptible to thermal degradation.

The hydrogen supply used in the present process may come from any convenient source, as for instance, by the disassociation of methane. If desired, any diluting gas may be used in connection with the hydrogen.

When the starting material has been subjected to the first cycle of hydrogen action that reduces coke residue, specific gravity and viscosity, the stripping of the beneficiated mass may be effected at any point desired, as for instance, at 200 C., or higher, or lower. Generally the point of stripping is determined by the boiling range desired in the product flowing from the final action of hydrogen in the second cycle.

The time element in the second cycle of hydrogen action, periods of two minutes have proven satisfactory to provide illustration of the present invention, however, longer or shorter periods may be used, as for instance, several minutes. Generally, the time element in the first cycle of hydrogen action is longer than in the second.

Within the limits of the boiling range of the finally beneficiated material, solvents and/or plasticizers may be fractionated therefrom, as for instance, to provide substitutes for the boiling ranges of any of the following:

Product: Boiling range C. Benzol 78-120 Toluol -150 Hi-fiash naphtha -200 High boiling crudes 150-290 Plasticizers -360 The residue incidental to aforesaid stripping action, or any residue incidental to solvent or plasticizer recovery from the finally beneficiated intermediate starting material may be recycled for further product production. By such recycling operation the coke residue inherent to the starting material can be made to substantially finally disappear.

Starting material includes tars and fractions thereof derived from wood, coal and petroleum including gases of carbon content; as for instance, Wood tar, pine tar, coke oven tar, gas house tar, Water gas tar and synthetic aromatic tars derived from petroleum sources including gases containing carbon.

Starting materials previously subjected to the action of hydrogen are suitable starting materials.

In the disclosures herein made the removing of low boiling fractions by gas movement or pressure release is considered the equivalent of distillation.

When reference is made to high molecular complexes as contained in the starting material, and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain. extent depolymerized by the solvent present.

An especially attractive manner of practicing the present process is to first depolymerize the starting material with a solvent; as an example, but not in a restrictive sense, a refractory solvent. Such use of a solvent may be employed up to volume for volume, or more. After such depolymerization, the solvent and solute are then subjected to process variables as noted in th foregoing. Such a procedure is especially attractive when treating a refined pitch.

Starting materials of the present process also include tars of aromatic content from which low boiling fractions have been removed, as for instance, tars from which solvent oils have been removed. Viewed broadly, the starting materials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to removal of low boiling fractions from the starting material, high boiling fractions and pitches.

The evaluation of solvent power is conveniently accomplished by finding the well-known aniline point or Kauributanol number. The evaluation of plasticizing properties is conveniently accomplished by recourse to methods suggested in Chapter VI, The Technology of Solvents by Dr. Otto Jordon, Mannheim, Germany, translated by Alen D. Whitehead, Chemical Publishing Company of New York, Incorporated, New York, New York.

Minor changes may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen at a pressure in excess of 50 atmospheres and a temperature chosen between 350-450 C. for a period not in excess of about three hours,.whereby to avoid loss of newly induced fractions; strlpping newly induced fractions from the beneficiated material; and subjecting at least a portion of said stripped fractions to the action of a relative low flow of hydrogen at a pressure of at least about 50 atmospheres and a temperature chosen between 465-535" C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range, to produce a solvent.

2. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; and subjecting at least a portion of said'stripped fractions to the action of a relatively low flow of hydrogen to'provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range; and fractionating the last named beneficiated material to segregate a solvent.

3. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises; subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen for a period not in excess of about three hours, whereby to avoid loss of newly induced fractions; stripping newly induced fractions from the beneficiated material; and subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range and fractionating the last named beneficiated material to provide a solvent boiling preponderantly between and C.

4. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high flow of hydrogen at a pressure in excess of about 50 atmospheres and a temperature chosen between about 350450 C. for a period not in excess of about three hours, whereby to avoid polymerization; stripping newly induced fractions from the beneficiated material; and subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen at a pressure of at least about 50 atmospheres and a temperature chosen between 465-535 C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range to produce a solvent.

5. In the production of a solvent from the refined pitch produced by stripping high temperature coal tar to at least about substantial dryness, and fractionating the overhead material to recover a liquid useful as a wood preservative, and a higher boiling fraction boiling predominantly above 355 C., the process which comprises: subjecting said higher boiling fraction to the action of a relatively high fiow of hydrogen at a temperature and pressure in excess of about 400 C. and about 50 atmospheres, respectively, for a period not in excess of about three hours, whereby. to avoid lowered hydrogen absorption; stripping newly induced fractions from the beneficiated material; and subjecting at least a portion of said stripped fractions to the action of a relatively low flow of hydrogen at a pressure of at least about 50 atmospheres and a temperature chosen between 465535 C. to provide an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range to produce a solvent.

JACQUELIN E. HARVEY, JR. 

